Still struggling with basics

The basics of look-and-feel are still a mystery to me –how to implement CSS, how to tweak appearance and functionalities displayed. It’s like any other medium: conceptual stuff seems daunting until you know the tricks, and then you wonder how you could have been so dense…
In this case it was a matter of a simple edit to the /mt/index.html file, to add /mt to the path for the stylesheet. I suppose it’s a win that I did figure it out…
…but now I can’t make it stick… when I SAVE this edit, it reverts to the vanilla form, without the formatting I specified. It’s probably something in the setup that I’m overlooking.
Moving the stylesheet to the directory above /mt/ seems to have done it…
Today’s activities mostly around globalization, but I also started thinking about words about music, and transcribed a vibrant passage from Miéville’s King Rat